If you use Varnish with an Apache server and analyze Apache log files (with AWstats or something else), you probably saw all requests were coming from 127.0.0.1 (or the IP address Varnish is on). You’ve probably forgotten to change the LogFormat you use.
Fortunately, Varnish adds an header on its request to Apache with the remote IP address in it. Just replace “%h” with “%{X-Forwarded-For}i” in the LogFormat and reload your server.